Similar to RS2300 4x4 post.

You will either need a network card which just plugs into the PCI slot at the back or one with your motherboard. Mine has a wireless motherboard so is done that way.

XP Home, was looking at this yesterday for someone at work and yes as RS2300 4x4 it contains less networking features than Pro amongst a couple of other things as well. Pro is geared for networking which is why it is used in offices.

Does you internet connection run from your router or each PC? I assume the router. Do you know the cable you are using to connect to the router i.e. CAT 5?

If so there is no reason from there why you cannot set a network up. Are the PC's in the same workgroup or domain etc. If so then try mapping to opposite drives. If the printer is running locally off the downstairs PC then it will most likely need to be on to recognise it however if it is networked off the router then it shouldnt matter.

Let me know how you get on

HTH